Resinous compositions of epoxy resin,high melting acid or anhydride of at least three carboxylic groups and aromatic hydrocarbon-aldehyde resin



United States Patent 3,487,125 RESINOUS COMPOSITIONS OF EPOXY RESIN,HIGH MELTING ACID OR ANHYDRIDE OF AT LEAST THREE CARBOXYLIC GROUPS ANDARO- MATIC HYDROCARBON-ALDEHYDE RESIN Joseph A. Verdol, Bolton, andDonald J. Carrow, Ivanhoe, Ill., assignors to Sinclair Research, Inc.,New York, N.Y., a corporation of Delaware N0 Drawing. Filed May 10,1967, Ser. No. 637,355 Int. Cl. (108g 45/04 US. Cl. 260-837 12 ClaimsABSTRACT OF THE DISCLOSURE A resinous composition of matter comprisingthe reaction product of an aromatic hydrocarbon-aldehyde resin; atpolyether ethoxyline resin containing epoxy groups of an epoxylatedmaterial selected from the class consisting of polyhydric alcohols andphenols containing at least two phenolic hydroxy groups; and apolycarboxylic acid or anhydride thereof having 3 to 100 carboxylic acidgroups.

This invention relates to the production of new and improved resinouscompositions by the inclusion of aromatic hydrocarbon-aldehyde resins insystems comprising polyether ethoxyline resins containing epoxy groups,and polycarboxylic acids or their anhydrides. These new and improvedresinous compositions are eminently suitable for use as molding,casting, coating, or laminating compositions.

In the art of preparing molding, laminating and coating compositionsfrom epoxy resins, the use of certain high melting polycarboxylic acidsor their anhydrides, such as trimellitic anhydride, pyromelliticanhydride and copolymers of styrene and maleic anhydride, as curingagents will produce cured compositions. The problem which results,however, is that polycarboxylic acids or their anhydrides have highmelting points and are not completely compatible with epoxy resins atambient temperatures. Because of these high melting points, it isusually necessary to heat the epoxy resin and the polycarboxylic acid orits anhydride to a temperature near the melting point of thepolycarboxylic acid or anhydride to obtain the necessary compatibilityfor use of the mixture in the preparation of castings, molds, coatings,lamimates and the like. Under these elevated temperature conditions, thechemical reaction between the epoxy resin and the anhydride proceedsvery fast. In most cases, the curing reaction occurs more rapidly thandesired and suitable castings, moldings, coatings, or laminates cannotbe prepared in the short time interval remaining after the high meltingacids or anhydrides and epoxy resins have been homogeneously mixed. As aresult, the cured compositions are usually brittle and have poor impactstrength.

In the present invention, it has been discovered that the inclusion of ahydrocarbon-aldehyde resin, such as xylene-formaldehyde resin as acomponent of a casting, molding, coating, or laminating compositioncomprising an epoxy resin and a polycarboxylic acid or anhydride, suchas trimellitic anhydride, pyromellitic anhydride or a copolymer ofstyrene and maleic anhydride, provides "ice improved compatibilitybetween the polycarboxylic acid or anhydride and the epoxy resin Whileat the same time producing an overall improvement in the physicalproperties of the cured composition. In this invention, thehydrocarbon-aldehyde resin enables an otherwise incompatible system tobe prepared at temperatures sufliciently low so as to allow a mostsatisfactory pot life prior to effecting the final cure of thecomposition.

In accordance with the invention, the advantages provided by the use ofa hydrocarbon-aldehyde resin in epoxy resin and polycarboxylic acid oranhydride compositions are manifold. The cost of the final compositionis reduced since a hydrocarbon-aldehyde resin such asxylene-formaldehyde resin can be produced more economically thaneitherthe epoxy resin or the polycarboxylic acid or anhydride. Theenhanced compatibility and long pot life which is attainable permitscasting, molding, coating, and laminating compositions to be pre-mixedand stored for extended time intervals prior to use. The incorporationof the hydrocarbon-aldehyde resin as part of the epoxy resin andcarboxylic acid or anhydride composition improves the physical andelectrical properties of the molding, casting, coating, or laminate. Forexample, one may incorporate the desired degree of flexibility in thefinal product without adversely affecting the impact resistance or heatof distortion of the formulation Also, many epoxy resinpolycarboxylicacid or anhydride systems which are ordinarily too brittle for practicalapplication can be made to possess outstanding physical propertiesthrough the incorporation of a hydrocarbon-aldehyde resin such as axylene-formaldehyde resin.

According to the invention, the new and improved resinous composition ofthe present invention comprise the reaction products of (a) an aromatichydrocarbonaldehyde resin, the aromatic-hydrocarbon resin often having amolar ratio of aromatic-hydrocarbon to aldehyde of about 25:1 to 1:100,preferably 5:1 to 1:5, and frequently having a molecular weight of about200 to 5000, preferably 250 to 1500; (b) a polyether ethoxyline resincontaining epoxy groups and comprising a polyether derivative of apolyhydric organic compound selected from the class consisting ofpolyhydric alcohols and phenols containing at least two phenolic hydroxygroups; and (c) a polycarboxylic acid or anhydride having 3 to 100carboxylic acid groups, preferably 3 to 20. The aromatichydrocarbon-aldehyde resin can comprise about 5 to percent, by Weight,of the composition, the polyether ethoxyline resin can comprise about 5to percent, by weight, of the composition, and the polycarboxylic acidor anhydride can comprise about 1 to 75 percent, by weight, of thecomposition.

Aromatic hydrocarbons which may be reacted with aldehydes to produce thelow cost aromatic hydrocarbonaldehyde resins found eminently suitable inpreparing the compositions of this invention often contain 6 to 16 or 20carbon atoms and include ortho-, meta-, and para-xylene individually,commercial xylene which is a mixture of the three xylenes plus a smallperecntage of ethylbenzene, naphthylene, alkyl-substituted naphthylenes,anthracene, alkyl-substituted anthacene, mesitylene, etc.

Aldehydes which may be used to advantage in preparing the instantaromatic hydrocarbon-aldehyde resins often contain about 1 to 20,preferably 1 to 5, carbon atoms and include aldehydes which readilyreact with 3 4 phenols to give phenol-aldehyde type resins. Suitablealdc- Ethoxyline resins which can be used in the invention hydes includealiphatic aldehydes, for example, formaldeinclude those described morefully in, for instance, Castan hyde, acetaldehyde, propionaldehyde,butyraldehyde, etc.; US. Patent 3,324,483, Castan US. Patent 2,444,333,

aromatic aldehydes, for example, benzaldehyde, etc.; and British Patent518,057 and British Patent 579,698. Esheterocyclic oxygen containingaldehydes such as furfural, sentially these ethoxyline resins are basedon the resinous etc. 5 product of reaction between theepihalogenohydrin, for

The aromatic hydrocarbon-aldehyde resin can be preinstanceepichlorohydrin and an aliphatic polyhydric alpared by condensing thearomatic hydrocarbon with the cohol, for example, glycerine or a phenolhaving at least aldehyde, for instance, pure m-xylene or commercialxytwo phenolic hydroxy groups, for example, bis-(4-hylene withformaldehyde (either aqueous, anhydrous, or droxyphenyl)dimethylmethane. Further examples of alcoholic), at a temperature ofabout 75150 C., prefethoxyline resins which may be employed in thepractice erably, 100-1 and a pressure of about 1 aim. to of the presentinvention are disclosed in US. Patents 100 atm. using acidic catalystswhich are capable of cf- 2,494,295; 2,500,600 nd 2,511,913. Byreference, the fecting sucha condensation reaction. Trifluoroacetic acidaforemgntioned patents are i d d to b part f the Pres or phosphoric acidare preferredcatalysts. When the arO- 5 em description of the ethoxylineresins used and, for matlc h y droarbon'aldehyde resin 11564 In Prepanngh brevity, the ethoxyline resins will not be described other compositionis xylene-formaldehyde, resin, the molar ratio than that they containmore th one epoxide group, e.g.,

of xylene to formaldehyde can be :1 to 1:100, preferably 5:1 to 1:5. Thearomatic hydrocarbon aldehyde resin can be isolated by separating theacid, washing with 20 water, followed by neutralization and stripping invacuo.

from one to two or more epoxide groups per molecule and may be preparedby effecting reaction between a phenol or polyhydric alcohol, forexample, phenol, hy- The reaction product is believed to contain hydroxydroquinone, resorciuol, glycerine, and condensation prodh l groups,methylene ether groups and methylene nets of phenols with ketones, forinstance, bis-(4-hydroxygroups which can be demonstrated in thefollowing P dlmethylmeihafie 19 With 61310111011)- structure: hydrin orother epihalogenohydrins. For example, the re- $113 (3H3 (EH3 n0eH2--ern-omoom@omo onto OLE- 3 a CH3 CH3 om H3 All of the above types of oxygenfunctional groups, as action of epichlorohydrin withbis-(4-hydroxyphenyl) di- Well as others may be present in thexylene-formaldehyde methylrnethane (bisphenol A) may be formulated asresins. No attempt has been made to present the various follows:

0 H3 H 9 CH3 0 position isomers which may occur. Needless to say, theywhere p has an average value varying from 0 to about are numerous andvaried. When preparing xylene-form- 10. Many of these ethoxyline resinsare sold under the aldehyde resins, the amount of oxygen which ispresent name of Epon resins. Data on several of the Eponresins in theresin and the concentration of hydroxyl groups found eminently suitablefor the practice of the invenwhich are incorporated within the resin canbe controlled tion are given in the table below:

TABLE I Resin type, Shell Color, 25 0. Average Viscosity at 25 ChemicalCo. Melting point, (Gardner) Epoxide molecular C., centipoises or EponC. (Durrans) (max. equivalent weight Gardner-Holdt Liquid 8 175-210350-400 4,00010,000. Liquid 12 175-210 350-400 5,000-15,000. Liquid 10225-290 450 Az-Ar.

40-50 8 300-375 700 Ai-B. 64-76 8 450-535 900-1000 C-G. -105 6 870-10251400 Q-U. -132 8 1650-2050 2900 Y-Z -155 11 2400-4000 3800 ZTZs.

The epoxide equivalent is the weight of resin in grams which contains 1gram chemical equivalent of epoxy It the resin chains are assumed to belinear with no side branching and it is further assumed that an epoxygroup terminates each end, then the'epoxide equivalent (weight) is onehalf of the average molecular weight of the resin. Epoxide equivalentsare determined by reacting a known quantity of resin with a knownquantity of hydrochloric acid and back-titrating the remaining acid todetermine its consumption.

to various degrees by adjusting acid concentration, tem- Polycarboxylicacids or anhydrides which may be used perature and the ratio of xyleneto formaldehyde emin the invention include trimellitic anhydride,pyromellitic ployed in the reaction. Insofar as the present inventionanhydride, and copolymers of styrene and maleic anis concerned, allxylene-formaldehyde resins appear to 70 hydride as well as otherpolycarboxylic acids or their impart beneficial properties to the finalepoxy formulaanhydrides having a melting point of at least about tion inwhich they are incorporated. However, those 50 C., preferably at leastabout C. Preparation of resins which contain some oxygen and hydroxylgroups the styrene-maleic anhydride copolymer can be by known arepreferred over those which do not contain functional methods. Apreferred method is by solution polymerizagroups. 75 tion where themonomers are polymerized in a suitable solvent employing as apolymerization catalyst a freeradical catalyst, such as a peroxide,preferably benzoyl peroxide; dicumyl peroxide or an alkyl peroxydicarbonate, at a temperature of about 75 to 300 C. or more. Suitablesolvents include the aromatic hydrocarbon solvents, such as cumene,p-cymene, xylene, toluene, etc. Other suitable solvents are the ketones,such as methyl ethyl ketone. The preferred manner of carrying out thepolymerization is by what is known as incremental feed addition. By thismethod the monomers and catalyst are first dissolved in a portion of thesolvent in which the polymerization is to be conducted and the resultingsolution is fed in increments into a reactor containing solvent heatedto reaction temperature, usually the reflux temperature of the mixture.

When an aromatic solvent is employed as the solvent for thepolymerization, the formation of the copolymer produces a heterogeneoussystem, the polymer layer being the heavier layer and recoverable bymerely decanting the upper aromatic solvent layer and drying. On theother hand, when a ketone is the solvent, the formed copolymer isusually soluble in the solvent media so that recovery of the productnecessitates a solvent-stripping operation. Styrene and maleic anhydrideare copolymerized in a molar ratio of styrene to maleic anhydride ofabout 1 to :1, preferably 1 to 3:1. The resulting copolymer can have amolecular weight of about 400 to 10,000 and a melting point of 50 C. to350 C. The kinematic viscosity at 30 C. of a 10 percent by weightsolution of the copolymer in acetone may range from 0.4 to 500centistokes, preferably 0.5 to 10.

The compositions of the invention are generally prepared by hotblending, temperatures of the order of from 50 C. to 200 C. arepreferred. Curing catalysts such as tertiary amines or amine salts,quaternary amine bases or salts may be used, if desired, to shorten thecuring time.

Coating and laminate applications normally employ organic solventsolutions of the compositions disclosed. The solvent or solvent blendemployed is chosen to provide the desired volatility, rheology,sprayability or other properties. Solvents which are suitable includearomatic hydrocarbons such as toluene and xylene, ketones such as methylethyl ketone, methyl isobutyl ketone, etc.

The compositions of the present invention may include other additivessuch as pigments, fillers, plasticizers and the like. Illustrativeexamples of pigments which are useful in the practice of this inventionare titanium dioxide, cadmium red, carbon black, light chrome green,iron blue, ultramarine blue, furnace black, and others. Conventionalsolid fillers suitably added to the compositions prepared according tothis invention include powdered metals, such as aluminum powder, andother finely divided materials such as asbestos, silicas, tales, variousclays, and the like. Plasticizers suitably added to the compositionsprepared according to this invention include phthalate esters, e.g.dibutyl phthalate and dioctyl phthalate; trimellitate esters, e.g.tributyl mellitate and trioctyl mellitate. Other suitable plasticizersare naphthenic oils, paraffinic oils, chlorinated paraflins, chlorinatedbiphenyls, chlorinated aromatics, polyesters, and polyethers.

In order that those skilled in the art may better understand how thepresent invention is practiced, the following examples are given by wayof illustration. All are parts by weight.

Example I A mixture of 8 parts of trimellitic anhydride and 25 parts ofEpon 820 (epoxide equivalent 190) was heated to 125150 C. in an attemptto form a viscous homogeneous mixture. It was very difficult to preparea casting in this manner since, in the absence of a xylene-formaldehyderesin, the trimellitic anhydride and epoxy resin reacted immediatelyduring the high temperature mixing step and the materials were alreadypartially cured before they could be placed into a mold.

6 Example II A xylene-formaldehyde resin was prepared by condensingequimolar amounts of trioxane and m-xylene with the use of 20 percent byweight of trifluoroacetic acid catalyst at C., under reflux. The productwas isolated by removing the acid and stripping off the unreactedxylene. Analysis of the resin was as follows: molecular weight-265,oxygen content0.2 percent, hydroxyl value0.4. A mixture of 8 parts oftrimellitic anhydride, 25 parts of Epon 820 and 10 parts of thexylene-formaldehyde resin was heated to -15 0 C. to form a viscoushomogeneous mixture. The liquid was placed in a mold for 12 hours at C.An extremely hard, clear, and tough casting was obtained which hadexcellent impact resistance. When the composition was placed in asolvent such as xylene or methyl ethyl ketone, sprayed or roll coated onmetal and wooden substrates, and baked for 5-30 minutes at 150200 C.,clear, flexible, and extremely tough coatings of varying thickness wereobtained.

Example III The xylene-formaldehyde resin was prepared in the samemanner as described in Example II. In this example, 8.6 parts oftrimellitic anhydride and 15 parts of the xylene-formaldehyde resin werepre-mixed and heated to 125-150 C. to form a viscous homogeneousmixture. To this mixture was added 30 parts of Epon 820 and theresulting viscous mixture was placed into a mold and cured for 1 hour at150 C. A hard, clear and tough casting was obtained which had extremelyoutstanding impact resistance as compared to a comparable castingprepared from trimellitic anhydride and Epon 820 in the absence of axylene-formaldehyde resin. When the composition was placed in a solventsuch as xylene or methyl ethyl ketone, sprayed or roll coated on metaland wooden substrates, and baked for 5-30 minutes at 150-200 C., clear,flexible, and extremely tough coatings of varying thickness wereobtained.

Example IV A xylene-formaldehyde resin was prepared by reactingequirnolar amounts of m-xylene and formaldehyde with about 30 percent byweight of phosphoric acid catalyst at 1-00-115 C. for about 18 hours.The product was isolated by separating the acid and washing with water,followed by neutralizing and stripping in vacuo. The final productshowed the following analysis: molecular weight339, hydroxyl value89,oxygen content5.4 percent. In this example, 8 parts of trimelliticanhydride and 10 parts of the xylene-formaldehyde resin were premixedand heated to 125-150 C. to form a viscous homogeneous mixture. To thismixture was added 25 parts of Epon 820 and the resulting viscous mixturewas placed into a mold and cured for 2 hours at 150 C. A hard, clear andtough high-impact casting was obtained. When the composition was placedin a solvent such as xylene or methyl ethyl ketone, sprayed or rollcoated on metal and wooden substrates, and baked for 5-30 minutes at150- 200 0., clear flexible, and extremely tough coatings of varyingthickness were obtained.

Example V A xylene-formaldehyde resin was prepared by reacting 1 mole ofm-xylene with 2 moles of paraformaldehyde with about 30 percent byweight of phosphoric acid catalyst at 100-115 C. for about 18 hours. Theproduct Was isolated by separating the acid and washing with water,followed by neutralizing and stripping in vacuo. The final productshowed the following analysis: molecular weight-477, hydroxyl value57,oxygen content 9.9 percent. Inthis example, 8 parts of trimelliticanhydride and 10 parts of the xylene-formaldehyde resin were pre-mixedand heated to l25150 C. to form a viscous homogeneous mixture. To thismixture was added 25 parts of Epon 820 and the resulting viscous mixturewas placed into a mold and cured for 2 hours at 150 C. A hard, clear andtough high-impact casting was ob tained. When the composition was placedin a solvent such as xylene or methyl ethyl ketone, sprayed or rollcoated on metal and wooden substrates, and baked for 5-30 minutes atISO-200 C., clear, flexible, and extremely tough coatings of varyingthickness were obtained.

Example VI The xylene-formaldehyde resin was prepared in the same manneras described in Example V. In this example, parts of pyromelliticanhydride and 10 parts of xyleneformaldehyde resin were pre-mixed andheated to 125- 150 C. to form a viscous homogeneous mixture. To thismixture was added 28 parts of Epon 820 and the resulting viscous mixturewas placed into a mold and cured for 2 hours at 150 C. A hard, clear,and tough high-impact casting was obtained. When the composition wasplaced in a solvent such as xylene or methyl ethyl ketone, sprayed orroll coated on metal and wooden substrates, and baked for 530 minutes at150-200 C., clear, flexible, and extremely tough coatings of varyingthickness were obtained.

Example VII The addition of xylene-formaldehyde resins to systemscomprising copolymers of styrene and maleic anhydride and epoxy resinsproduced compositions with greatly improved impact resistance, tensilestrength and flexibility.

Table II below summarizes the results of a series of experiments whereinthe copolymer of styrene and maleic anhydride employed was one having amolar ratio of styrene to maleic anhydride of about 1:1 and a molecularweight of about 700. The xylene-formaldehyde resin was 8 resultingmixture was placed in a mold and cured for 24 hours at 100 C. A hard,clear, and tough casting was obtained which possessed greatly improvedphysical properties over a casting prepared which did not containxylene-formaldehyde resin.

It is claimed:

1. A resinous composition comprising the reaction product of:

(a) an aromatic hydrocarbon-aldehyde resin;

(b) a high melting polycarboxylic acid having 3 to 100 carboxylic acidgroups or anhydride thereof, having a melting point of at least about 50C.; and

(c) a polyether ethoxyline resin containing epoxy groups of anepoxylated material selected from the class consisting of polyhydricalcohols and phenols containing at least two phenolic hydroxy groups;

the aromatic hydrocarbon-aldehyde resin comprising about 5 to 75 percentby Weight of the composition, the high melting polycarboxylic acid oranhydride thereof comprising about 1 to 75 percent by weight of thecomposition, and the polyether ethoxyline resin comprising about 5 to 90percent by weight of the composition.

2. The resinous composition of claim 1 wherein said aromatichydrocarbon-aldehyde resin is xylene-formaldehyde resin.

3. The resinous composition of claim 1 wherein said polyether ethoxylineresin is the reaction product of bisphenol A and epihalogenohydrin.

4. The resinous composition of claim 1 wherein said high meltingpolycarboxylic acid or anhydride thereof is trimellitric acid or itsanhydride.

5. The resinous composition of claim 1 wherein said high meltingpolycarboxylic acid or anhydride thereof is prepared in the same manneras described in Example V. pyl'omellitic acid or its anhydride- TABLEII.EPOCOY CASTINGS CONTAINING XYLENEJPORMALDEHYDE RESINS AND POLYMER 0FSTYREN [Cured at 24 hours and 150 0.]

E AND MALEIC ANHYDRIDE Control #1 #2 #3 Result Sari? A: 820 20 20 20 20pon Copolymer of styrene and maleic 5 5 5 5 All cured impact anhydr1d6properties. Xylene-formaldehyde resin- 0 2. 5 5 7. 5 Series B:

Epon 820 20 20 20 20 Copolymer of styrene and maleic 10 1O 10 10 Allcured and had good anhydride. impact properties. Xylene-formaldehyderesin 2. 5 5 7. 5 Series C:

Epon 820 20 20 20 20 Copolymer of stryene and maleic 15 15 15 15 Doanhydride. Xylene-formaldehyde resin 2. 5 5 7. 5 Series D:

Epon 820 20 20 20 20 Copolymer of sytrene and maleic 20 20 20 20 Allcured and had only fair anhydride. impact properties.Xylene-formaldehyde resin 0 2. 5 5 7. 5

* A copolymer of styrene and maleic anhydride having a molar ratio ofstyrene to maleic anhydride of about 1:1 and a molecular weight of about700.

The xylene-formaldehyde resin was prepared in the same manner asdescribed in Example V. Fifty parts of xylene-formaldehyde resin andparts of a copolymer of styrene and maleic anhydride having a molarratio of styrene to maleic anhydride of about 1:1 and a molecular weightof about 1600 were pre-mixed at 200 C. A solid reaction product wasobtained which was ground to a fine powder and mixed with 25 parts ofEpon 820. The

6. The resinous composition of claim 1 wherein said high meltingpolycarboxylic acid or anhydride thereof is styrene-maleic anhydridecopolymer having a molecular weight of about 400 to 10,000, a molarratio of styrene to maleic anhydride of about 10:1 to 1:1, and a meltingpoint of about 50 C. to 350 C.

7. The resinous composition of claim 1 comprising the reaction productof said polyether ethoxyline resin and a. homogeneous mixture of saidaromatic hydrocarbonaldehyde resin and said high melting polycarboxylicacid or anhydride thereof.

8. A resinous composition comprising the reaction product of:

(a) xylene-formaldehyde resin;

(b) a high melting polycarboxylic acid or anhydride thereof selectedfrom the group consisting of (i) trimellitic acid and its anhydride,(ii) pyromellitic acid and its anhydride and (iii) styrene-maleicanhydride copolymers having a molecular weight of about 400 to 10,000, amolar ratio of styrene to maleic anhydride of about 3:1 to 1:1, and amelting point of about 50 C. to 350 C., and

(c) a polyether ethoxyline resin containing epoxy groups of anepoxylated material selected from the class consisting of polyhydricalcohols and phenols containing at least two phenolic hydroxy groups;the xylene-formaldehyde resin comprising about 5 to 75 percent by weightof the composition, the high melting polycarboxylic acid or anhydridethereof comprising about 1 to 75 percent by weight of the composition,and the polyether ethoxyline resin comprising about 5 to 90 percent byweight of the composition.

9. The resinous composition of claim 8 wherein said polyether ethoxylineresin is the reaction product of bisphenol A and an epihalogenohydrin.

10. The resinous composition of claim 8 comprising the reaction productof said polyether ethoxyline resin and a homogeneous mixture ofxylene-formaldehyde resin and trimellitic acid or its anhydride.

11. The resinous composition of claim 8 comprising the reaction productof said polyether ethoxyline resin and a homogeneous mixture ofxylene-formaldehyde resin and pyromellitic acid or its anhydride.

12. The resinous composition of matter of claim 8' comprising thereaction product of said polyether ethoxyline resin and a homogeneousmixture of xylene-formaldehyde resin and said styrene-meleic anhydridecopolymer.

References Cited UNITED STATES PATENTS MURRAY TILLMAN, Primary ExaminerPAUL LIEBERMAN, Assistant Examiner US. Cl. X.R.

